Disruptions to the circadian rhythm can lead to altered metabolism. Modification of thyroid function may be a reason why circadian misalignment may contribute to future metabolic disorders. We investigated whether circadian disruption through constant light (LL) can lead to variations in hormone levels associated with thyroid function. Mice were exposed to LL or a 12:12 Light:Dark (LD) cycle for 6 weeks; then glucose tolerance and thyroid hormone levels were measured at ZT 6 and ZT 18. There was day/night variation in glucose tolerance, but LL had no effect. LL reduced TSH, increased fT4, and abolished day/night variation in fT3 and leptin. These findings illustrate that LL alters thyroid-related hormones, providing evidence of a link between circadian disruption and thyroid function.

Hurricane Matthew (28 Sep – 9 October 2016) was perhaps the most infamous storm of the 2016 Atlantic hurricane season, claiming over 600 lives and causing over $15 billion USD in damages across the central Caribbean and southeastern U.S. seaboard. Research surrounding Matthew and its many noteworthy meteorological characteristics (e.g., rapid intensification into the southernmost Category 5 hurricane in the Atlantic basin on record, strong lightning and sprite production, and unusual cloud morphology) is ongoing. Satellite remote sensing typically plays an important role in the forecasting and study of hurricanes, providing a top-down perspective on storms developing over the remote and inherently data sparse tropical oceans. In this regard, a relative newcomer among the suite of satellite observations useful for tropical cyclone monitoring and research is the Visible/Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB), a sensor flying onboard the NOAA/NASA Suomi National Polar-orbiting Partnership (SNPP) satellite. Unlike conventional instruments, the DNB's sensitivity to extremely low levels of visible/near-infrared light offers new insight on storm properties and impacts. Here, we chronicle Matthew’s path of destruction and peer through the DNB’s looking glass of low-light visible observations, including lightning connected to sprite formation, modulation of the atmospheric nightglow by storm-generated gravity waves, and widespread power outages. Collected without moonlight, these examples showcase the wealth of unique information present in DNB nocturnal low-light observations without moonlight, and their potential to complement traditional satellite measurements of tropical storms worldwide.

Breast cancer (BC) incidence rates in Connecticut are among the highest in the United States, and are unevenly distributed within the state. Our goal was to determine whether artificial light at night (ALAN) played a role. Using BC records obtained from the Connecticut Tumor Registry, we applied the double kernel density (DKD) estimator to produce a continuous relative risk surface of a disease throughout the State. A multi-variate analysis compared DKD and census track estimates with population density, fertility rate, percent of non-white population, population below poverty level, and ALAN levels. The analysis identified a “halo” geographic pattern of BC incidence, with the highest rates of the disease observed at distances 5-15 km from the state's major cities. The “halo” was of high-income communities, with high ALAN, located in suburban fringes of the state's main cities.

In humans and most other species, changes in the intensity and duration of light provide a critical set of signals for the synchronisation of the circadian system to the astronomical day. The timing of activity within the 24 h day defines an individual's chronotype, i.e. morning, intermediate or evening type. The aim of this study was to investigate the associations between environmental light exposure, due to geographical location, on the chronotype of university students. Over 6 000 university students from cities in the Northern Hemisphere (Oxford, Munich and Groningen) and Southern Hemisphere (Perth, Melbourne and Auckland) completed the Munich ChronoType Questionnaire. In parallel, light measures (daily irradiance, timing of sunrise and sunset) were compiled from satellite or ground stations at each of these locations. Our data shows that later mid-sleep point on free days (corrected for oversleep on weekends MFSsc) is associated with (i) residing further from the equator, (ii) a later sunset, (iii) spending more time outside and (iv) waking from sleep significantly after sunrise. However, surprisingly, MSFsc did not correlate with daily light intensity at the different geographical locations. Although these findings appear to contradict earlier studies suggesting that in the wider population increased light exposure is associated with an earlier chronotype, our findings are derived exclusively from a student population aged between 17 and 26 years. We therefore suggest that the age and occupation of our population increase the likelihood that these individuals will experience relatively little light exposure in the morning whilst encountering more light exposure later in the day, when light has a delaying effect upon the circadian system.